We all know water is essential to life, and adequate water intake is very important in hot weather , but it is just as important in cold weather, maybe even more important. In the warm months horses are getting a portion of their water from grazing, but when subsisting on hay their needs increase. Inadequate water can contribute to impaction colic, and that's life threatening.
Young, growing horses and senior horses with worn teeth can be more sensitive to cold water and not want to drink (Ever drink ice water with a sensitive tooth?). Water trough heaters are essential in cold climates. Just breaking the ice won't suffice. I am quite surprised at some of the prominent horsemen/women who don't have a clue about this.
Our automatic waterers are heated, and all our troughs are heated except one (The Norwegian Fjord prefers ice water.... must be genetic.). Even the water buckets in the barn are heated. I added up and came to the conclusion that we're using over 10,000 watts in drinking water heating alone. Allegheny Power must love us.